Prosthetic valves have been used for many years to treat valvular disorders. Native valves, including heart valves (such as the aortic, pulmonary, tricuspid, and mitral valves), serve critical functions in assuring the forward flow of an adequate supply of blood through the cardiovascular system. These valves can be rendered less effective by congenital, inflammatory, or infectious conditions. Such damage to the valves can result in serious cardiovascular compromise or death. For many years the definitive treatment for such disorders was the surgical repair or replacement of the valve during open heart surgery, but such surgeries are prone to many complications.
Transvascular techniques have also been developed for introducing and implanting a prosthetic valve using a flexible catheter in a manner that is less invasive than open-heart surgery. For example, a prosthetic valve can be mounted in a crimped state on the end-portion of a flexible catheter and advanced through a blood vessel of the patient until the prosthetic valve reaches the implantation site. The prosthetic valve at the catheter tip can then be expanded to its functional size at the site of the defective native valve such as by inflating a balloon on which the prosthetic valve is mounted. Alternatively, the prosthetic valve can have a resilient, self-expanding stent or frame that self-expands the prosthetic valve to its functional size when advanced from a delivery sheath at the distal end of the catheter.
Prosthetic valves generally consist of a cylindrical stent-like frame and leaflets. The leaflets typically have fixed, inflow edges that are sutured continuously along an interior circumference of the cylindrical frame. Blood flows through the prosthetic valve when all the leaflets open and lie against the inner surface of the prosthetic valve frame, creating a single, circular channel. Conversely, the prosthetic valve closes when the leaflets are deflected inwardly and coapt against each other, similarly to a native heart valve. Unfortunately, prosthetic valves can suffer from paravalvular leaks (PVL), or blood leaking around the outside of the prosthetic valve. A need therefore exists for a stented bioprosthetic valve which minimizes PVL and/or other sources of regurgitation through the prosthetic valve.